Shocking is a completely inadequate word to use when describing Polly Stenham’s two-act ‘tragi-comedy’.

That Face takes every possible upper-middle class neuroses and amplifies each and every one, by a thousand plus one. The play reaches the point where tragedy and comedy also seem like barely adequate genres to suggest. A better definition would be an encapsulation of ‘deranged modernity’ – but that’s less Oxford-English.

Alcoholism, bullying, sexual perversity, Oedipal desire, a lack of love, a lack of dignity, and eventually a loss of face. All are chronicled with startling brutality and relentless repugnance. I was tempted to use the word ‘honesty’ for one moment – but is this really an honest play?

Stenham said that the main purpose of That Face was to “write about a class of people I hadn’t often seen represented in the theatre,” as if the alienated, tortured middle-class has historically been a literary anomaly.

That’s not to say that the play doesn’t fulfil a very basic function of stirring and startling and emotionally excavating the audience. That Face felt like the biggest possible slap in the face.

The play follows mother Martha (Frances Barber), who likes to drink, a lot, and boarding school drop-out son Henry (James Norton), who has become her full-time carer and almost-lover. Henry’s sister Mia (Leila Mimmack) isn’t loved by mummy, and has been forgotten by rich daddy, which incites her (or so we are meant to infer) to engage in a terrible initiation prank on a younger girl, which leads to hospitalisation and looks dangerously like torture.

Director Richard Wilson of unforgettable One Foot in The Grave fame must get a mention for his commendable ability to temper Stenham’s youthful extremism with well-paced execution – and a very useful revolving stage.

The play’s climax becomes a horrific hotchpotch of incest, addiction and desperation. The most staggering part is undoubtedly the final scene, where we see James Norton portray a deeply moving emotional disintegration, climaxing in the image of him stood like a baby in his mother’s night clothes and jewels, wetting himself in front of his devastated sister, delirious mother, and flabbergasted father.